Gaudio

Pure Go audio library with a simple and easy to use API (inspired by pydub)

import "github.com/zeozeozeo/gaudio"

Supported formats

Audio formats:

• MP3 (go-mp3)
• FLAC (flac)
• WAV (go-dsp/wav and go-wav)

Tracker formats:

• MOD (gomodplay and Gotracker)
• XM (Gotracker)
• S3M (Gotracker)
• IT (Gotracker)

Examples

Create a segment from path

import (
    "github.com/zeozeozeo/gaudio"
)

// Create a segment from path (see supported formats)
segment, err := gaudio.LoadAudioFromPath("audio.mp3", gaudio.FormatMP3)
if err != nil {
    panic(err)
}

Create a segment from a reader

// Open file
file, err := os.Open("song.mp3")
if err != nil {
    panic(err)
}
defer file.Close()

// Create a segment (see supported formats)
segment, err := gaudio.LoadAudio(file, gaudio.FormatMP3)
if err != nil {
    panic(err)
}

Overlay segment2 over segment1 at the 3rd second

segment1.Overlay(segment2, 3)

Clone a segment

clone := segment.Clone()

Concatenate segments

// Concatenate segment at the start of another segment
segment1.ConcatenateStart(segment2)

// Concatenate segment at the end of another segment
segment1.ConcatenateEnd(segment2)

// Concatenate segment at the specified second of another segment (3.5th second)
segment1.ConcatenateAtSecond(segment2, 3.5)

Detect and remove silence

threshold = 0.01 // Silence threshold

// Get leading and trailing silence
leading, trailing := segment.DetectSilence(threshold)

// Get leading silence
leading := segment.DetectSilenceStart(threshold)

// Get trailing silence
trailing := segment.DetectSilenceEnd(threshold)

// Remove silence
segment.RemoveStartAndEndSilence(threshold)
segment.RemoveStartSilence(threshold)
segment.RemoveEndSilence(threshold)

Calculate BPM (warning: can be slow)

// minBpm: the minimum BPM you expect (120)
// maxBpm: the maximum BPM you expect (200)
// steps: the amount of steps per interval (1024)
// samplesPerBeat: the amount of samples used for a single beat (1024)
bpm := segment.CalcBPM(120, 200, 1024, 1024)

Apply echo effect

// delay: delay between echo layers (0.05)
// layers: amount of layer (2)
segment.EchoEffect(0.05, 2)

Pitch to note note (needs testing)

// Pitch formula: 2 ** (key / 12)
segment.ApplyNote(12)

Export a segment to a file (only wav files are supported right now)

file, err := os.Create("output.wav")
if err != nil {
    panic(err)
}
defer file.Close()

segment.Export(file, gaudio.FormatWAVE)

Apply fade in / fade out effect

// start float64: the amount of fade-in seconds
// end float64: the amount of fade-out seconds
segment.Fade(0.5, 1) // Fade in for 0.5 seconds, fade out for 1 second

// This is equal to...
segment.FadeIn(0.5)
segment.FadeOut(1)

Invert phase

segment.InvertPhase()

Reverse

segment.Reverse()

Repeat segment n times

segment.Repeat(5)

Change speed (speedup, slowdown)

// Change speed by two times
segment.SetSpeed(2)

// Slow down
segment.SetSpeed(0.25)

Take a slice out of a segment

// Take a slice from the 1st second to the 2nd second (the length of the slice will be 1 second)
slice := segment.Slice(1, 2)

Trim (cut)

// Remove everything between the first second and the 1.5th second
segment.Trim(1, 1.5)

// Remove first 3 seconds
segment.TrimStart(3)

// Remove last 2.3 seconds
segment.TrimEnd(2.3)

Empty segment

// Sample rate, channels
gaudio.Empty(44100, 2)

Silent segment

// Returns a silent segment with the length of 5.5 seconds, 44100 sample rate, and two channels
gaudio.Silent(5.5, 44100, 2)

Raw data

Raw data is stored in float32 in segment.Data, and is structured like that:

[channel 1 value, channel 2 value, channel 1 value, channel 2 value, ...]

Audio formats

const (
	FormatFLAC AudioFormat = 1 // .flac
	FormatWAVE AudioFormat = 2 // .wav
	FormatMP3  AudioFormat = 3 // .mp3
	FormatRAW  AudioFormat = 4 // Custom format

	// Tracker formats
	FormatMOD          AudioFormat = 5 // ProTracker .mod, rendered with gomodplay. This is faster than gotracker, but less accurate.
	FormatGotrackerMod AudioFormat = 6 // ProTracker .mod, rendered with Gotracker. This is slower than gomodplay, but more accurate.
	FormatS3M          AudioFormat = 7 // ScreamTracker III .s3m, rendered with Gotracker
	FormatXM           AudioFormat = 8 // FastTracker II .xm, rendered with Gotracker
	FormatIT           AudioFormat = 9 // ImpulseTracker .it, rendered with Gotracker
)

TODO

• Tests, benchmarks, profiling
• Fix speed being rounded up to integers
• More effects
• Support more formats (while staying 100% Go)